Poll: 28% of Republicans don't believe Obama was born in U.S.

A new Research 2000 poll, sponsored by the site DailyKos, finds broad traction among Republican voters for the belief that President Obama was not born in the United States.

The survey of American adults asked, "Do you believe that Barack Obama was born in the United States of America or not?" It found that 77% of Americans answer affirmatively, 11% say "no," with the balance unsure.

Notably, that 11% closely tracks the -- extremely stable -- share of the electorate that thought Obama was a Muslim, bolstering the notion that there's a certain share of the party's base (and this may well hold for both parties) that isn't about to let facts get in the way of negative views of a president of the opposite party.

The poll has a margin of error of plus/minus 2%, and a larger one for the subgroups, but here's the estimate of how broadly held the conspiracy theory, broken down by party:

Yes No Not sure Dem 93 4 3 Rep 42 28 30 Ind 83 8 9

With nearly a third of Republicans believing the theory, you can see why Republican politicians are inclined to treat it with some respect.